Rice hulls, a byproduct in the preparation of rice grains, has found many uses. One particular use is as a cleaning scouring abrasive in mechanics' handsoaps, wherein the rice hulls are ground to pass 20 but not 100 mesh, in amounts of 10 to 25% by weight of the soap composition, as disclosed in chapter 12 page 331 of Rice Chemistry and Technology, Edited by D. F. Houston, published by American Association of Cereal Chemists, Inc., St. Paul, Minn., 1972. Another use for finely ground hulls, described on page 332 of this same book, is as a filler in plastics and plywood glues. Still another use is as a carrier or adsorbent for materials ranging from vitamins to pesticides to explosives. However, there is no disclosure of the use of finely ground rice hulls as an abrasive in dentifrice compositions.
The prior art also discloses the use of cereal meal or soybean meal in dentifrice formulations as shown in U.S. Pat. No. 2,154,168; comminuted vegetable substances (cereal) such as rice, maize or corn is disclosed in U.S. Pat. No. 1,693,349; and a mixture of powdered rice, beans and bones is disclosed in U.S. Pat. No. 1,664,182. Natural fibers such as orris root, arrow root and vegetable fiber in dentifrices is disclosed in U.S. Pat. No. 1,523,840, No. 1,529,486 and No. 1,522,410. U.S. Pat. No. 2,436,818 also discloses the use of small amounts of a particular fraction of dehulled oats as a beneficial ingredient in dentifrices.
Although the prior art discloses natural products as an ingredient in dentifrices, said products do not include rice hulls, a byproduct in the preparation of rice grains. More specifically, rice grains are obtained by first dehulling and then debranning the rice product. It is the rice hulls that are the subject matter of this invention.